package com.shoppingwebsite.servlet;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.lang.reflect.Method;

/**
 *     基本映射路径
 */
public class BaseServlet extends HttpServlet {
    @Override
    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        /*
            应用反射的方法
            若访问的路径为 http://localhost:8080/travel/user/add
        */
        //完成方法分发
        //1、获取请求路径
        String uri = req.getRequestURI();            // 为/travel/user/add

        //2、获取方法名称
        String methodName = uri.substring(uri.lastIndexOf('/') + 1);        //为add，为uri中最后一个/字符的索引开始截取右边的字符串

        //3、获取方法对象method  （this是调用的类对象，也就是UserServlet）
        try {
            //获取方法
            Method method = this.getClass().getMethod(methodName, HttpServletRequest.class, HttpServletResponse.class);   //获得类对象的方法名
            //4、执行方法
            method.invoke(this, req, resp);           //invoke调用
        } catch (Exception e){

        }
    }

    /**
     * 直接将传入的对象序列化为json，并且写回给客户端
     *
     * @param obj
     */
    public void writeValue(Object obj, HttpServletResponse response) throws IOException {
        ObjectMapper mapper = new ObjectMapper();
        response.setContentType("application/json;charset=utf-8");
        mapper.writeValue(response.getOutputStream(), obj);
    }

    /**
     * 直接将传入的对象序列化为json，返回
     *
     * @param obj
     * @return
     */
    public String writeValueAsString(Object obj) throws JsonProcessingException {
        ObjectMapper mapper = new ObjectMapper();
        return mapper.writeValueAsString(obj);
    }
}
